JPH04283771A - Electrophotographic recording device - Google Patents

Abstract

PURPOSE:To obtain the electrophotographic device which can use light emitting elements with small chip area, enables their individual replacement even if the light emitting element has variance in light emission intensity, enables the light emitting elements to be arrayed on conditions that their intervals are sufficient, reduces the width of a carriage where the light emitting elements are mounted, and uses a small-sized, lightweight, inexpensive, and low-output driving motor. CONSTITUTION:A shift block 74 is provided on the surface of a photosensitive body 1 across a light guide 7. This shift block 74 is supported by a block 5a, a leaf spring 5b, etc., and LEDs 3 having one light emission part for each chip are arrayed across the carriage in parallel in the direction of the rotary shaft of the photosensitive body 1. This shift block 4 is moved by feeding electricity to a piezoelectric element and the LEDs 3 are blinked to form an electrostatic latent image on the surface of the photosensitive body 1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording apparatus in which light emitting elements such as LEDs are arranged at intervals of a plurality of dots and these light emitting elements are moved back and forth in the direction in which they are arranged.

0002

2. Description of the Related Art As an electrophotographic recording device of this type, there is, for example, Utility Model Application No. 58-58553, in which every other dot is
By reciprocating the array that has accumulated D, LE
A technique for reducing the number of D and drivers is disclosed.

0003

However, in the conventional device described above, a large number of LEDs are enclosed in one chip to form an array, so the chip area does not decrease. As is well known to those skilled in the art, it is important to reduce the chip area in order to reduce the manufacturing cost of semiconductors, but the above-mentioned conventional technology does not pay attention to this point, and therefore the manufacturing It was not possible to significantly reduce costs. Another disadvantage is that even if one light emitting element in the chip breaks, the entire chip must be replaced. Furthermore, in order to print one line, a large number of chips are required, but at this time, the variation in luminous intensity is usually small within a chip, but the variation between other chips is large, which is a problem. Since it is necessary to add a correction circuit for each case or to select and use chips with approximately the same emission intensity, there is a drawback that the cost further increases.

[0004] Furthermore, when chips are arranged side by side, gaps are created between adjacent chips, resulting in areas where printing is not possible.
It is necessary to arrange each chip in a staggered manner, and the carriage carrying the light-emitting elements becomes wider, larger, and heavier, and the driving motor must be an expensive, high-power one. It was necessary to use it.

[0005]

[Means for solving the problem] Regarding a photoconductor such as a photoconductor drum whose surface continuously moves, and the direction of movement of this photoconductor,
A plurality of light emitting elements such as LEDs are arranged at equal intervals in the right angle direction, and the light emitting parts thereof are provided facing the photosensitive surface, and the arranged light emitting elements are reciprocated in the arrangement direction and in the direction perpendicular to the arrangement direction. In the electrophotographic recording apparatus, light-emitting elements each having one light-emitting portion per chip are arranged at equal intervals as the light-emitting elements.

[0006]

[Operation] In the present invention, light-emitting elements having one light-emitting part per chip are arranged at equal intervals, and the arrayed light-emitting elements are caused to emit light while reciprocating in the arrangement direction and in a direction perpendicular to the arrangement direction. Therefore, high-density printing is possible even with an extremely small number of light emitting elements. Since there is only one light emitting element per chip, a light emitting element with a small chip area can be used. Furthermore, even if the light emitting element is damaged or the light emitting intensity of the light emitting element varies, each chip can be replaced individually. Also, ensure sufficient spacing between the light emitting elements and
It is possible to arrange them in rows.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a plan view of a first embodiment of the present invention, and FIG. 2 is a perspective view thereof. In FIGS. 1 and 2, 1 is a cylindrical photoreceptor rotated at a constant speed by a motor (not shown), 2 is a carriage placed opposite to the photoreceptor 1, and 3 is a light-emitting surface of the carriage 2 whose light-emitting surface is photosensitive. Light emitting diodes (hereinafter referred to as LEDs) are arranged one by one every 64 dots in the longitudinal direction so as to face the body 1, 4 is a carriage 2
A frame body 4a surrounding the frame body 4a, two first leaf springs 4b which are located between the frame body 4a and the carriage 2 and press down the carriage 2; Vertical shift driving means 5 includes a first piezoelectric element 4c that drives the carriage 2 upward; 5 is an L-shaped first block 5a; one end is fixed to one end of this first block 5a, and the other end is fixed to the frame body. An L-shaped second leaf spring 5b is fixed to the right end of block 4a, and a second leaf spring 5b is fixed to the other end of the first block 5a and deforms when a voltage is applied from a power source (not shown) to deform the second leaf spring 5b. A horizontal shift drive means 6 includes a laminated second piezoelectric element 5c that vibrates the carriage 2 from side to side; A spring support mechanism consisting of an L-shaped second block 6b that supports a three-plate spring 6a; 7 is a selfoc that is located between the carriage 2 and the photoreceptor 1 and guides the light emitted from the LED 3 to the surface of the photoreceptor 1; It is a light guide such as a lens (registered trademark of Nippon Sheet Glass Co., Ltd.), and this light guide is fixed to a frame (not shown).

As for the operation of the embodiment having the above configuration, first, the photoreceptor 1 is rotated at a constant speed by a motor (not shown). After reaching constant rotation speed, the carriage is rotated by applying a voltage having the waveform shown in FIG. 3(a) to the first piezoelectric element 4c and applying a voltage having the waveform shown in FIG. 3(b) to the second piezoelectric element 5c. 2 is shifted up and down while reciprocating in the direction of the rotation axis of the photoreceptor 1. That is, when a voltage that increases linearly is applied to the first piezoelectric element 4c, the first piezoelectric element 4c expands in the stacking direction, so that the carriage 2 shifts upward in stages while deforming the first leaf spring 4b. . When a voltage increasing stepwise in 64 steps is applied to the second piezoelectric element 5c in synchronization with this operation, the second piezoelectric element 5c expands little by little, and the frame body 4a is moved to the left while deforming the second leaf spring 5b. Move to. In this manner, each time the carriage 2 is moved by one of the 64 steps, the LED 3 emits light, and the photoreceptor 1 is exposed to one dot through the light guide 7. When this is done in 64 steps, a line of 64 dots is formed for each LED on the photoreceptor 1, and one straight line is formed over almost the entire width of the photoreceptor 1 as a whole. When the voltage applied to the first piezoelectric element 4c is suddenly reduced to zero after the 64-step movement is completed, the first piezoelectric element 4c rapidly shrinks to its original shape, and the carriage 2 is moved by the force of the first leaf spring 4b. Rapidly descends by one dot. Next, the first piezoelectric element 4c
When a linearly increasing voltage is again applied to the first piezoelectric element 4c, the first piezoelectric element 4c expands again in the stacking direction, so that the carriage 2 continuously shifts upward while deforming the first leaf spring 4b. In synchronization with this operation, when a voltage that descends stepwise in 64 steps is applied to the second piezoelectric element 5c, the second piezoelectric element 5c contracts little by little, and the force of the second leaf spring 5b causes the frame 4a to be moved again. moves to the right. In this way, each time the carriage 2 is moved one step out of the above 64 steps, the LED
3 is emitted, and the photoreceptor 1 is exposed to one dot through the light guide 7. When this is done for 64 steps, the photoreceptor 1 has L
A straight latent image line of 64 dots is formed for each ED, and one more straight line is formed over almost the entire width of the photoreceptor 1 as a whole. When the voltage applied to the first piezoelectric element 4c is suddenly reduced to zero after the 64-step movement is completed, the second piezoelectric element 5c rapidly shrinks to its original shape, and the carriage 2 is moved by the force of the first plate spring 4b. Rapidly descends by one dot. By repeating such operations, lines are formed one after another on the photoreceptor 1. Of course, since the light emission of the LED 3 is controlled according to the image data to be printed, a latent image is formed on the photoreceptor 1 according to the image data.

Thereafter, the image is developed using a known developing device (not shown).
The toner is transferred to the paper by the transfer device, fixed by the fixing device, and then the paper is discharged.

FIG. 4 is a diagram showing the movement of the carriage 2, and shows that the carriage 2 repeats a series of movements in which it moves upward to the right, descends, moves upward to the left, and descends again.

FIG. 5 is a perspective view showing the connection relationship between the first leaf spring 4b, the frame body 4a, and the carriage 2. The first leaf spring 4b is fixed to the first frame body 4a by rivets or welding. However, with respect to the carriage 2, as shown in the figure, a pin 2a attached to the carriage 2 is configured to be able to move in the longitudinal direction within a long hole 4d formed in the first leaf spring 4b. . FIG. 6 is a plan view of the carriage 2. When the printing density is 300 dpi, the printing width is 184 mm, and 64 dots are printed using one LED, the LE
34 pieces of D3 are arranged at intervals of about 5.42 mm.

It should be noted that the number of LEDs 3 being 34 is merely an example, and it goes without saying that the number may be larger or smaller depending on the print width, the speed of the photoreceptor, or the dot density.

FIG. 7 is a block diagram showing an example of a drive circuit suitable for the first embodiment. In FIG. 7, 8 is a CPU constituted by a microprocessor that incorporates a ROM for storing programs and a RAM for temporarily storing data for calculations. 8b, a third counter 8c, and a direction flag 8d. 9a and 9b are CP
a first DA converter and a second DA converter that convert digital data output from U8 into analog voltage;
10a and 10b are each a first DA converter 9a
and a first and second driver for power amplifying the output of the second DA converter 9b, the first driver 10a drives the first piezoelectric element 4c, the second driver 10b drives the second piezoelectric element 5c, and the first DA converter 9b Values set in the input registers of converter 9a and second DA converter 9b are expressed as DAC1 and DAC2.

The operation of this drive circuit will be explained with reference to the flowchart of FIG. For explanation, the first counter 8a and the second counter 8a
The values of the counter 8b, third counter 8c, and direction flag 8d are expressed as CT1, CT2, CT3, and DF, respectively.

Now, in step 1, the first counter 8a, the second counter 8b, the third counter 8c, and the direction flag 8d are cleared, and the first DA converter 10a and the second D/A converter 10a and the second D/A converter 10a are cleared.
Set 0 to A converter 10b. Since the first piezoelectric element 4c and the second piezoelectric element 5c are now in the most contracted state, the carriage 2 is at the right end and at the lowest position.

In step 2, it is checked whether printing is possible. If there is some abnormality in the device, the process ends without printing, but if printing is possible, the process proceeds to step 3.

In step 3, the value CT of the first counter 8a
1 is incremented by 1, and the value CT1 of the first counter 8a is set to the value CT1 of the first counter 8a.
Set it in the DA converter 9a. As a result, the 1st DA
The converter 9a converts the voltage corresponding to the value 1 to the first driver 1.
0a, the first driver 10a amplifies the power and supplies it to the first piezoelectric element 4c. Therefore, carriage 2
increases by one level.

In step 4, the value CT of the first counter 8a
It is checked whether 1 is equal to 1024, and if they are equal, the process proceeds to step 5, where the direction flag 8d is set.
The value DF of is inverted from 0 to 1 (or 1 to 0), and the first
The counter 8a value CT1 is set to 0 and the process proceeds to step 6. If the value CT1 is smaller than 1024, nothing is done and the process proceeds to step 6.

In step 6, the value CT of the second counter 8b is
Add 1 to 2.

In step 7, it is checked whether the value CT2 of the second counter 8b is equal to 16. If it is equal to 16, the process proceeds to step 8, but if it is smaller than 16, nothing is done.
Proceed to step 9. In step 8, turn off LED3,
The value CT2 of the second counter 8b is set to 0, and the process proceeds to step 9.

In step 9, it is checked whether the value DF of the direction flag 8d is 0 or 1. The value DF of the direction flag 8d is 0
If so, proceed to step 10 and set the value C of the third counter 8c.
T3 is incremented by 1 and the process proceeds to step 12. direction flag 8d
If the value DF is 1, the process proceeds to step 11, where the value CT3 of the third counter 8c is subtracted by 1, and the process proceeds to step 12.

In step 12, the second DA converter 9b
Set the value CT3 of the third counter 8c to
Proceed to step 3.

In step 13, the LED 3 is turned on, and either another process is performed or the time is adjusted in idle mode, and then the process returns to step 2. As a result, the second DA converter 9b
outputs a voltage corresponding to the value CT3 of the third counter 8c to the second driver 10b, and the second driver 10c amplifies the power of this and supplies it to the second piezoelectric element 5c. Element 5c expands and moves carriage 2 to the left (or right).

Now, by repeating the above operation, the first counter 8a increases until the value reaches 1024, and when it reaches 1024, it reflects the value DF of the direction flag 8d (here, it is reset to 0). Also, every time the value CT2 of the second counter 8b becomes 16, the value CT2 of the third counter 8c
3 is added or subtracted by 1 depending on the value DF of the direction flag 8d. Since the value DF of the direction flag 8d does not change until the value CT1 of the first counter 8a exceeds 1024 as described above, the value DF of the third counter 8c
is ultimately added from 0 to 63, and then subtracted from 63 to 0. Since the values of the first counter 8a and the third counter 8c change in this way, the first piezoelectric element 4c
expands almost linearly in 1024 steps, and the carriage 2 rises almost continuously by 1 dot, but on the other hand, the second piezoelectric element 5c changes only 64 steps within the same time; Therefore, the carriage 2 is moved stepwise to the right or left by one dot 64 times.

Further, the LED 3 is turned off while the carriage 2 is moving to the right or left, and is turned on in accordance with print data until the carriage 2 moves next time.

Furthermore, since the processing time from step 2 to step 13 is adjusted in step 13, while the first counter 8a counts 1024, the carriage 2
The distance that the surface of the photoreceptor 1 moves can be made equal to the distance that the surface of the photoreceptor 1 moves during that time, so that the surface of the photoreceptor 1 is relatively stationary. Therefore, in the case of this embodiment, it is desirable to use a type of LED that emits light from the entire joint surface, and to make the light emitting surface a perfect circle or square.

[0027] Once all the print data has been printed in the manner described above, printing becomes impossible in step 2, and the process ends after turning off the LED in step 14.

Regarding the synchronization of the photoreceptor 1 and the carriage 2, the drive control of the photoreceptor 1 and the carriage 2 may be performed by the same CPU, but the drive of the photoreceptor and the drive of the carriage may be controlled by separate CPUs. You can also use the CPU.

Furthermore, in order to synchronize the movement in the arrangement direction and the light emission timing of the first and second driving means and the light emitting element in the movement direction of the photoreceptor, a sensor is provided at each movement origin and this is used as a synchronization origin. You can also do that.

Although the above flowchart has been described as open loop control, the rotation amount of the photoreceptor 1 may be detected by a sensor, and this detection signal may be fed back to control the movement of the carriage 2.

In addition, in the above drive circuit, for example, if the rotational speed of the photoreceptor is doubled and each counter is added by 2 instead of 1, printing can be performed at 1/2 the printing density but at twice the speed, which reduces the use of toner. The amount will also be halved.

[0032] Also, each counter can be set to 1 without changing the rotation speed.
If you add and subtract 2 instead of adding and subtracting, you can print at 1/2 the printing density without changing the printing speed. In this case as well, the amount of toner used is reduced to 1/2.

Similarly, by varying the degree of counting of the counter with respect to the rotational speed of the photoreceptor, 100 DPI,
200DPI, 300DPI, 400DPI, 600D
It becomes possible to print at printing densities such as PI and 1200DPI. Also, in the above explanation, one line of printing is 10
Although the explanation has been made using 24 steps, this is to simplify the explanation, and normally the control is more finely controlled, and the value added or subtracted by each counter is not limited to 1.

Although bidirectional printing is performed in the above embodiment, a voltage having the waveform shown in FIG. 9(a) is applied to the first piezoelectric element 4c, and a voltage having the waveform shown in FIG. 9(b) is applied to the second piezoelectric element 5c. Unidirectional printing is also possible by applying voltage. In unidirectional printing, the vertical lines do not shift even if the LED 3 is installed poorly, so the vertical ruled lines can be printed neatly in one straight line. Therefore, a switch is provided to select between normal mode and high-speed printing mode, and this switch can be operated manually or electrically switched from a host system such as a personal computer.If printing quality is to be improved, unidirectional printing can be used. If you want to increase the printing speed, it is better to print in both directions. Furthermore, in unidirectional printing, it is necessary to return the carriage 2 to the right or left end, but since the stroke is large, it is difficult to return the carriage 2 quickly. For this reason, printing cannot be performed during the time Tr required for recovery, and the dot pitch in the row direction becomes coarse, so it is better to lower the rotational speed of the photoreceptor 1.

Furthermore, in the embodiment described above, a piezoelectric element was used as a drive source for moving the shift block 4 left and right, but if a sufficient stroke cannot be obtained with the piezoelectric element, for example, as shown in FIG. 13, the motor 11 ( For example, the shift block 4 may be moved left and right as a mechanism for converting the rotation of a pulse motor (pulse motor) into reciprocating motion by the eccentric cam 12, or the shift block 4 may be moved left and right by the linear motor 13 as shown in FIG. You can do it like this.

As the drive source for shifting the shift block 4 up and down, piezoelectric elements are superior in that they can digitally control minute distances in multiple stages, but various motors such as pulse motors and DC motors can be used.

Furthermore, the first piezoelectric element 4c and the second piezoelectric element 5c
It has two drive sources, but any substantially independent drive sources may be used.For example, the rotation of one motor is converted into reciprocating linear motion by an eccentric cam to vibrate the carriage from side to side. Further, the carriage may be shifted up and down by coupling an electromagnetic clutch and a gear to this motor to extract power intermittently and to make the driving direction reversible.

Furthermore, instead of moving the carriage in 64 steps, it may be moved continuously. In this case, the formed dots spread out horizontally, causing so-called tailing, so use a type of LED that emits light from the end surface of the joint, and the joint surface is aligned in the direction along the rotation direction of the photoreceptor. It is preferable to install it so that In other words, this type of LED 3' emits light with an intensity distribution spread in the direction along the joint surface 3a as shown in FIG. 6, so it becomes an ellipse as shown by hatching.
When the carriage 2 is moved from side to side while emitting D3', the area including the wavy line is exposed to light due to the trailing, so the dots become close to perfect circles and the print quality is improved.

Furthermore, if an LED with a condensing lens is used, a light guide such as a SELFOC lens (registered trademark of Nippon Sheet Glass Co., Ltd.) is also unnecessary.

Furthermore, in the embodiment shown in FIG.
Since the shift block 4 is vibrated along a plane passing through the rotation axis of the photoreceptor 1 with the bent portion of the third plate spring 6b as the center of rotation, the shift block 4 and the photoreceptor 1 can be seen microscopically as they vibrate. There is a risk that the distance between the two objects will change, causing defocus. In such a case, as shown in FIG. 12, the second leaf spring 5b' whose mounting direction is changed by 90 degrees
The shift block 4 may be supported in a reciprocating manner by the third plate spring 6a'.

Furthermore, in the above embodiment, the carriage 2 is moved vertically and horizontally in units of one dot.
The dots may be moved in units of 1/2 or 1/3 of the dots so that the dots overlap. That is, one or more intermediate dots may be formed between basic dots.

[0042]

As described in detail above, according to the present invention, there is provided a photoreceptor whose surface continuously moves, and a plurality of photoreceptors arranged at equal intervals in a direction perpendicular to the direction of movement of the photoreceptor. a light emitting element provided so as to face the photosensitive surface;
In an electrophotographic recording apparatus including a driving means for reciprocating the arrayed light emitting elements in the array direction and in a direction perpendicular to the array direction, one light emitting element is used for each chip.
Since light emitting elements each having a number of light emitting parts are arranged every multiple dots, a light emitting element with a small chip area can be used.
Furthermore, even if the light emitting elements are damaged or the light emission intensity of the light emitting elements varies, they can be replaced individually. Furthermore, if the light emitting elements are spaced sufficiently apart, it becomes possible to arrange the light emitting elements in a row, which reduces the width of the carriage on which the light emitting elements are mounted, making it not only smaller but also lighter in weight. There is an effect that an inexpensive low-output motor can be used for the drive motor.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a first embodiment of the present invention.

[Fig. 2] Perspective view of the first embodiment

[Figure 3] Voltage waveform applied to the first and second piezoelectric elements

[
FIG. 4 Diagram showing the movement of carriage 2

[Fig. 5] First leaf spring 4b, frame 4a, and carriage 2
A perspective view showing the connection relationship with

[Fig. 6] Plan view of carriage 2

[Figure 7] Block diagram showing an example of a drive circuit

[Figure 8] Flowchart explaining the operation of the drive circuit

[Figure 9] Voltage waveform applied to the first and second piezoelectric elements in unidirectional printing

[Figure 10] LED light emission intensity distribution diagram

[Figure 11] Cross-sectional view showing the mounting direction of the LED

[Figure 12
] A perspective view of essential parts of a second embodiment of the present invention

FIG. 13 is a perspective view of the main parts of the third embodiment of the present invention.

FIG. 14 is a perspective view of the main parts of the fourth embodiment of the present invention.

[Explanation of symbols]

1 Photoreceptor 2 Carriage 3 LED 4 Shift block 5 First driving means 5a 1st block 5b Second leaf spring 5c Second piezoelectric element 6 Spring support mechanism 6a 3rd leaf spring 6b 2nd block 7. Light guide 8 CPU

Claims (1)

[Claims] 1. A photoreceptor whose surface moves continuously, and a plurality of light-emitting elements arranged at equal intervals in a direction perpendicular to the direction of movement of the photoreceptor, the light-emitting parts of which are arranged to face the photoreceptor surface. and a driving means for reciprocating the arrayed light emitting elements in the array direction, wherein light emitting elements each having one light emitting part per chip are arranged at regular intervals as the light emitting elements. An electrophotographic recording device characterized by: